Self respect.

I have been dating this girl for a year, she left yesterday. Over the year, the more time we spent together, the more I care about her, the more she seemed to realize it and took advantage. She would treat me poorly, she never kept a single promise she made me, and she would constantly make me the bad guy and everything was my fault. I would do plenty of nice things for her, and I would always be there for her when she was upset, but if I ever said "could you be nicer? I mean I have done ______ for you, it would be nice if you weren't so rude", and she would respond with "well I didn't ask you to" or she would get mad saying I was only doing those things to hold over her. She would call me names, leave the house at the slightest hint of an argument. She has said she has wanted to hit me, but during arguments she would talk about how she was afraid of me when I never ever raised a finger to her. She has made me feel like everything is my fault, that I some how deserve her treating me this way. I always do this, I always let me get so close that I'll hold on to them through everything. At the expense of my mental health, my self esteem, and I'd out my life on the back burner to try and help her with hers. Every time this happens I promise myself I'll never do it again, but then someone comes by and it's a repeat. I don't know what's wrong with me, I don't know why I even care that she blocked me off everything and left. I feel like I'm a fuck up. I don't know what to do.